Floyd Mayweather Jr. Lights $100 Bill ... ON FIRE

7/12/2011 5:00 AM PDT

Floyd Mayweather Jr. Lights $100 Bill ... ON FIRE

A recession-proof Floyd Mayweather Jr. literally has money to burn -- and proved it by setting a $100 bill on FIRE inside an Atlanta nightclub this weekend.

Floyd was partying with Lil Kim and Gucci Mane at the Velvet Room during the conflagration Sunday night -- and we're told, there were plenty more bills where that came from ... Floyd was rolling with STACKS of hundreds.

We should mention: it's illegal to burn money ... so if the Feds decide to pursue an investigation, Floyd could face up to six months behind bars, and, ironically, a $100 fine.